[Al Skierkiewicz]

At 1 MPS, the wire all by itself has inductance. The series inductance and the parallel capacitance sets the line impedance. I use twisted pair shielded cable for a variety of applications, mostly audio. Typical cable has an impedance that is approaching 60 ohms with a parallel capacitance of ~23pf per foot. Ironically, a low impedance transmitter sending into the bus will "see" a 60 ohm load when the bus is terminated at both ends. This is similar to the twisted pair the phone company has used for more than a century. They found that terminating in 600 ohms (about 10 times the actual line impedance) they were able to minimize line loss while getting a flat response if they maintained a source impedance of the same load. I linked a TI CAN document in another thread that shows the waveform distortion with mis-matched loads.